1. Field of the Invention
The present inventive concept relates to an apparatus and method that forms images based on a detection of characteristics of the fed printing medium (for example, size, skew and/or shift of the printing medium) and/or based on a detection of detection patterns.
2. Description of the Related Art
A printer may use printing medium of different standard formats and may be equipped with at least one printing medium feed unit that loads the printing medium. The printing medium feed unit may include a cassette on which a standard format printing medium is loaded and a multipurpose tray on which a printing medium of a nonstandard format may be loaded. The printer receives the printing medium from the printing medium feed unit for a printing image.
However, the printing medium may have a format different from the expected format set by the user during a print job. For example, a printing medium having a size smaller than the print image may have been loaded into the cassette, unknown to the user setting the print job for the print image. When the image is printed on the loaded printing medium, portions of the printing image will be missing. In addition to the waste of the unwanted printed image, the inside the image forming apparatus is undesirably polluted as a result of the printing operations exterior to the printing medium.
Also, when the printing medium is fed, the printing medium may be skewed during its transport. Here again, a part of the printed image may fail to align with the printing medium thus obtaining similar poor results; the printed printing medium may become useless since the print image is not properly printed and undesirable contamination of the interior of the image forming apparatus may occur.
In order to solve the mentioned problem in feeding the printing medium, various arts of detecting a state of feeding have been introduced. The published examples are, a method controlling an image forming timing by detecting a leading edge of the printing medium and a method using a detected width of the printing medium for image forming.
Especially, the present applicant has disclosed an apparatus and a method detecting the feeding state of the printing medium through United States Patent Publication No. US 2006/0289813 A1 (published date: Dec. 28, 2006, titled of “PAPER DETECTION APPARATUS AND PRINTING METHOD”) including detecting a way of feeding a printing medium, a printing medium size and a printing medium skew, to prevent a printing error owing to disagreement between the printing medium size and an image size, and the skew of the printing medium.
Further, in an electro-photographic color image forming apparatus, particularly, in a single path electro-photographic color image forming apparatus, a color registration method to align overlapped color images has been suggested to solve a misalignment problem of color images of respective colors when forming a full color image. However, conventional methods of color registration demands a complex arithmetical operation and/or has a problem of being sensitive to an error produced by a noise component in a registration mark.